A multi-proxy approach to decipher global sea-level and ice-volume dynamics during late Cenozoic “snapshot” intervals based on benthic foraminiferal calcite from ODP Site 849

人类对地球气候的影响越来越大，导致全球变暖，从而导致极地冰盖融化和全球海平面上升。为了保护沿海地区在变暖的未来不受海平面上升的影响，需要准确预测未来海平面的变化。因此，该项目旨在更好地了解比今天更温暖的世界中的海平面和冰量动态。为此，将对过去500万年地球历史中6个关键的冰川-间冰期循环（海洋同位素阶段（MIS）1-5、MIS 29-31、MIS 57-59、MIS 99-101、MIS M1-MG 1和MIS CN 5-CN 7）的海平面/冰量变化进行重建。这些晚新生代的“快照”间隔产生决定性的不同背景条件的全球冰量，但包括阶段，代表密切类似于一个变暖的未来方面的轨道配置，大气温室气体浓度和/或温度。拟议的研究将以从东赤道太平洋（大洋钻探方案849号地点）的一个岩芯中取得的保存完好的底栖有孔虫的地球化学分析为基础。更确切地说，氧同位素分析将与镁/钙和“聚集同位素”得出的深海温度相结合，以得出海水的氧同位素组成，这是全球冰量和海平面变化的代用指标。这种多代理方法包括两个独立的古温度计（镁/钙和“聚集同位素”），以测试从氧同位素中提取的温度信号的准确性，以得出海平面变化。因此，它代表了相对于以前的海平面重建技术向前迈出的关键一步，并可能有助于解决晚新生代海平面记录中的不一致性，因为它们仍然可用。最后，为该项目的个别晚新生代“快照”间隔生成的记录将揭示低频（冰川间冰期）海平面/冰量变化，但也与人类相关的时间尺度连接的高频变化。因此，该项目将提供进一步的线索，以实现一个完整的机制（冰川间冰期到千年尺度）的全球海平面/冰量动态的理解相关的整体背景下，不久的将来变暖。

The increasing influence of humans on Earth's climate causes global warming and hence melting of polar ice sheets and a rise in global sea levels. To protect coastal regions from rising seas in a warming future, accurate projection of future sea-level change is needed. Therefore, this project aims to better understand sea-level and ice-volume dynamics in a world that is warmer-than-today. For this purpose, sea-level/ice-volume change will be reconstructed for six critical glacial-interglacial cycles from the past 5 million years of Earth’s history (Marine Isotope Stages (MIS) 1–5, MIS 29–31, MIS 57–59, MIS 99–101, MIS M1–MG1, and MIS CN5–CN7). These late Cenozoic “snapshot” intervals yield decisively different background conditions in terms of global ice volume, but include phases that represent close analogues to a warming future with regard to orbital configuration, atmospheric greenhouse-gas concentration and/or temperature. The proposed study will be based on the geochemical analysis of well-preserved benthic foraminifera retrieved from a drill core in the Eastern Equatorial Pacific Ocean (Ocean Drilling Program Site 849). More precisely, oxygen-isotope analysis will be combined with Mg/Ca- and “clumped-isotope”-derived deep-sea temperatures to yield the oxygen-isotope composition of seawater, which is a proxy for global ice-volume and hence sea-level change. This multi-proxy approach includes two independent paleothermometers (Mg/Ca and “clumped isotopes”) to test the accuracy of the temperature signal extracted from oxygen isotopes to derive sea-level change. It therefore represents a critical step forward with respect to previous sea-level reconstruction techniques and will likely help to resolve inconsistencies in late Cenozoic sea-level records as they are yet available. Finally, records to be generated for the individual late Cenozoic “snapshot” intervals of this project will reveal both low-frequency (glacial-interglacial) sea-level/ice-volume changes, but also high-frequency variabilities connected to human-relevant timescales. The project will thus provide further clues to achieve a full mechanistic (glacial-interglacial to millennial-scale) understanding of global sea-level/ice-volume dynamics relevant within the overall context of near-future warming.